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Astrophysics > High Energy Astrophysical Phenomena

Title:Gamma-ray Astronomy: Implications for Fundamental Physics

Abstract: Gamma-ray Astronomy studies cosmic accelerators through their electromagnetic
radiation in the energy range between ~100 MeV and ~100 TeV. The present most
sensitive observations in this energy band are performed, from space, by the
Large Area Telescope onboard the Fermi satellite and, from Earth, by the
Imaging Air Cherenkov Telescopes MAGIC, H.E.S.S. and VERITAS. These instruments
have revolutionized the field of Gamma-ray Astronomy, discovering different
populations of gamma-ray emitters and studying in detail the non-thermal
astrophysical processes producing this high-energy radiation. The scientific
objectives of these observatories include also questions of fundamental
physics. With gamma-ray instruments we study the origin of Galactic cosmic
rays, testing the hypothesis or whether they are mainly produced in supernova
explosions. Also, we obtain the most sensitive measurement of the cosmic
electron-positron spectrum between 20 GeV and 5 TeV. By observing the gamma-ray
emission from sources at cosmological distances, we learn about the intensity
and evolution of the extragalactic background light, and perform tests of
Lorentz Invariance. Moreover, we can search for dark matter by looking for
gamma-ray signals produced by its annihilation or decay in over-density sites.
In this paper, we review the most recent results produced with the current
generation of gamma-ray instruments in these fields of research.